Riot police drive protesters out of Istanbul's Taksim Square

ISTANBUL, Turkey -- Turkish riot police firing tear gas and water cannon took less than half an hour on Saturday to bring to an end an 18-day occupation of an Istanbul park at the centre of the strongest challenge to Prime Minister Recep Tayyip Erdogan's 10-year tenure.

The protests, which began as an environmental sit-in to prevent a development project at Taksim Square's Gezi Park, quickly spread to dozens of cities and spiraled into a broader expression of discontent about what many say is Erdogan's increasingly authoritarian decision-making.

He vehemently denies the charge, pointing to his strong support base which allowed him to win his third consecutive term with 50 per cent of the vote in 2011.

The protests, which left at least four people dead and more than 5,000 injured, dented Erdogan's international reputation and infuriated him with a previously unseen defiance to his rule.

For more than two weeks, protesters had flouted Erdogan's warnings to vacate the area. On Saturday evening, he ran out of patience.

As dusk fell, hundreds of white-helmeted riot police swept through Taksim Square and Gezi Park, firing canisters of the acrid, stinging gas as they stormed through the tents set up throughout the park.

Thousands of peaceful protesters, choking on the fumes and stumbling among the tents, put up little physical resistance, even as plain-clothes police manhandled many to drive them from the park. Just moments before, the park had been full of protesters young and old, as well as families with children.

Many ran into nearby hotels for shelter. A stand-off developed at one hotel on the edge of the park, where police opened up with water cannon against protesters and journalists outside before throwing tear gas at the entrance, filing the lobby with white smoke. At other hotels, plain-clothes policemen turned up outside, demanding the protesters come out.

Some protesters ran off into nearby streets, setting up makeshift barricades and running from water cannon, tear gas and rubber bullets into the early hours of Sunday. Plumes of white tear gas rose from the streets.

As news of the raid broke, thousands of people from other parts of Istanbul gathered and were attempting to reach Taksim. Television showed footage of riot police firing tear gas on a highway and bridge across the Bosphorus to prevent protesters from heading to the area.

Demonstrations also erupted in other cities. In Ankara, at least 3,000 people swarmed into John F. Kennedy street, where opposition party legislators sat down at the front of the crowd facing the riot police -- not far from Parliament. In Izmir, thousands converged at a seafront square.

Near Gezi, ambulances ferried the injured to hospitals as police set up cordons and roadblocks around the park, preventing anyone from getting close.

Tayfun Kahraman, a member of Taksim Solidarity, an umbrella group of protest movements, said an untold number of people in the park had been injured -- some from rubber bullets.

"Let them keep the park, we don't care anymore. Let it all be theirs. This crackdown has to stop. The people are in a terrible state," he told The Associated Press by phone.

Taksim Solidarity, on its Web site, called the incursion "atrocious" and counted hundreds of injured -- which it called a provisional estimate -- as well as an undetermined number of arrests. Istanbul governor's office said at least 44 people were taken to hospitals for treatment. None of them were in serious condition, it said in a statement.

Huseyin Celik, the spokesman for Erdogan's Justice and Development Party, told NTV that the sit-in had to end.

"They had made their voice heard ... Our government could not have allowed such an occupation to go on until the end," he said.

As the tear gas settled, bulldozers moved into the park, scooping up debris and loading it into trucks. Crews of workmen in fluorescent yellow vests and plain-clothes police went through the abandoned belongings, opening bags and searching their contents before tearing down the tents, food centres and library the protesters had set up in what had become a bustling tent city.

It was a violent police raid on May 31 against a small sit-in in Gezi Park that sparked the initial outrage and spiraled into a much broader protest. While those in the park have now fled, it was unclear whether their fervour had been doused, whether they would take their movement to other places, or try to return to the park at a later time.

Saturday's raid came less than two hours after Erdogan threatened protesters in a boisterous speech in Sincan, an Ankara suburb that is a stronghold of his party.

"I say this very clearly: either Taksim Square is cleared, or if it isn't cleared then the security forces of this country will know how to clear it," he told tens of thousands of supporters at a political rally.

A second pro-government rally is planned in Istanbul Sunday. Erdogan has said the rallies were not designed as "an alternative" to the demonstrations at Gezi Park, but part of early campaigning for local elections next March -- though he used the occasion to both criticize the protesters and praise his supporters.

"You are here, and you are spoiling the treacherous plot, the treacherous attack!" he told the cheering crowd, insisting unspecified groups both inside and outside Turkey had conspired to mount the protests -- and that he had the documents to prove it.

The crowd chanted in response: "Stand straight, don't bow, the people are with you!"

According to the government's redevelopment plan for Taksim Square that caused the sit-in, the park would be replaced with a replica Ottoman-era barracks. Under initial plans, the construction would have housed a shopping mall, though that has since been amended to the possibility of an opera house, a theatre and a museum with cafes.

On Friday, Erdogan offered to defer to a court ruling on the legality of the government's contested park redevelopment plan, and floated the possibility of a referendum on it. The protesters felt those concessions were not enough, however, and vowed to press on. But that was before the raid ousted them.